SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02999dc9e9910d5c6057e65cc9baef318f5ce322545f8d2fd2b4042650fb56a2' 
  AND token = 'l6EzVNlsi2/VnGYoafhD6elovWwrdq11yfSUWwZAjZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}